Sigurður Guðjónsson

Challenges for fish in warmer waters: the case of the Arctic char

Sigurður Guðjónsson

Institute of Freshwater Fisheries, Iceland

Global warming and climate change will affect the distribution and the
abundance of many important fish populations. To assess biodiversity responses
to climate change in northern regions, a NordForsk funded research program,
NordChar, was initiated and is ongoing on the fish, Arctic char (Salvelinus alpinus). The Arctic char was
chosen as a model species due to its wide distribution, which is relatively
little influenced by anthropogenic factors, and char is very plastic with both
phenotypic and genotypic responses to environmental change. The Arctic char, as
other salmonid species, is also an important and highly evaluated fish in the
northern regions. In this study, both genetic and biological parameters were
investigated to map the species variability. Biological and life history
characteristics are extracted from the extensive literature. For the genetic
mapping, mitochondrial DNA (mtDNA) was used as it interacts with the energy
system of the cell. Genetic characters can therefore be expected to be
sensitive to environmental temperature conditions in poikilotherms such as
Arctic char.The genetic work involves
two phases. In the first phase, we sequenced the whole mtDNA genome of 128
individuals, chosen to represent geographically and phylogenetically the
biodiversity of the species. This robust overview of the genetic variation
revealed that some parts of the mtDNA are very variable and in total 468 SNP’s
was found. In the second phase, a detailed analysis was done of the
phylogenetic and differentiation among populations within and among locations
across the species range using selected highly variable areas of the mtDNA.At the same time this is an explorative
genome scan to detect candidate loci for adaptation along then gradient of latitude or environmental temperature.Preliminary
results show highly diverged lineages with regional distribution but moderately
diverged lineages can be widely distributed geographically.Furthermore moderately diverged lineages can
be sympatric within the same watershed. The findings will be compared to
different life history patterns. The study has produced a genetic tool that can
be used to monitor adaptive genetic divergence in Arctic char.Furthermore, the findings will improve
understanding on what happens as climate changes both for Arctic char and other
fish species.